This research proposal is an experimental investigation into: (1) the identification of synaptic transmitter actions, including recently implicated peptides, on neurons in the vertebrate retina; (2) the ionic mechanism and conductance changes associated with transmitter action will be studied using intracellular recording techniques; (3) morphological-physiological correlations will be made using horseradish peroxidase single cell staining techniques, applies to neurons that have been studied for rod-cone input and response to pharmacological agents; (4) the extracellular K ion activity changes which result from light-and dark-evoked neuronal activity will be studied with K ion selective electrodes combined with pharmacological techniques which restrict retinal activity to small, well defined populations of neurons. The goal of this research is to provide information on the transmitters which may subserve inteneuronal communication and the neuronal events which may contribute to neuronal-glial inteactions which underly components of the electroretinogram.